Authorities discover fourth border tunnel in one week near Nogales

NOGALES, AZ - Federal authorities have unearthed an unfinished border tunnel near Nogales making it the fourth tunnel found in a week.

U.S. Immigration and Customs Enforcement spokeswoman Amber Cargile said the Homeland Security Investigations-led Nogales Tunnel Task Force found the incomplete tunnel on Friday while inspecting a drainage system in Mexico. She said no drugs were found and it appears as if the tunnel's construction was in its early stages.

Earlier this week, federal officials found three sophisticated drug smuggling tunnels equipped with lighting and ventilation. Two were found in the San Diego-Tijuana area, and another was found in a vacant strip mall storefront in the southwestern Arizona city of San Luis.

Cargile said the investigation into the Nogales tunnel was ongoing. No arrests have been made.